The foot point of a continental slope is the most important boundary point in delimitation of the continental shelf 200 nautical miles away, which may affect the precision of 60 nautical mile lines extrapolated from the foot point of the continental slope and 1% sediment thickness contours as well as the final outer limit. To perform intelligent analysis on the two-dimensional topography section so as to automatically recognize the foot point of the continental slope has important application values both on the aspect of the delimitation of the continental shelf exceeding 200 nautical miles, automatic recognition of the two-dimensional topography section features and two-dimensional topography section drawing.
It is stipulated in Article 76 of United Nations Convention on the Law of the Sea signed into the law in 1982 that: “the continental shelf of a coastal state comprises the seabed and subsoil of the submarine areas that extend beyond its territorial sea throughout the natural prolongation of its land territory to the outer edge of the continental margin, or to a distance of 200 nautical miles from the baselines from which the breadth of the territorial sea is measured where the outer edge of the continental margin does not extend up to that distance.” If the coastal state proposes that the distance exceeds 200 nautical miles from the baselines from which the breadth of the territorial sea is measured, then the outer edge of the continental shelf excluding 200 nautical miles should be delimited according to relevant requirements of Article 76 of the United Nations Convention on the Law of the Sea and Article 4 of its annex, and a delimitation proposal should be submitted to the UN Commission on the Limits of the Continental Shelf.
The key evidence for the delimitation of the continental shelf exceeding 200 nautical miles is series of delimitation limits, comprising the foot point of the continental slope (referred to as FOS), formula lines (FOS+60M line and 1% sediment thickness contours), boundary lines (350M line and 2500 m+100M line) and outer limit and the like. The FOS is the most important boundary point because the FOS is the origin for determining the series limit of the continental shelf exceeding 200 nautical miles. The FOS will directly affect the accuracy of the FOS+60M lien and the 1% sediment thickness contours, and finally affect the coordinates of the outer limit and the determined area. If the FOS is wrong or has larger error, it may generate significant impact on the final outer limit.
Analyzed from the retrieved public data, at present, there are no mature technical methods used for automatic recognition of the foot point of the continental slope domestically. Although the delimitation of the continental shelf excluding 200 nautical miles is introduced in few literatures, faithful contents of the method for automatically generating the foot point of the continental slope are lacked, and the prior art is not sufficient to support the recognition and generation of the foot point of the continental slope.